|Never we do mention something about the value of a used instrument without any previous investigation, otherwise any hint would be most dubious!|
Used instruments can have both: a very high as well as a small ("trash-") value. The correct decision is to ask your piano technician nearby for an exact inspection/investigation.
Parts for self-restoring your old piano are mostly not getable. They are made by hand either by piano factories or by special manufacturers (i.e. keys or action). In these cases we are unable to help.